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Geared Candleholder 


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Geared Candleholder 

Written By: Benjamin Cowden 


Band saw (1) 

C-clamp (1) 

Caliper (1) 

Center punch (1) 

Combination square (1) 

Drafting divider (1) 

Drill press (1) 

Hacksaw (1) 

Hammer (1) 

Metal files (1) 

Metal scribe (1) 

Oval drafting template (1) 

Protractor (1) 

Respirator mask (1) 

Sandpaper (1) 

Scotch-Brite scouring pad (1) 
or steel wool 

Scrap board (1) 
or plywood 



Aluminum plate (1) 
for the body and gears 

Aluminum plate (1) 
for the candleholders 

Aluminum rod (1) 
for the feet 

Aluminum bar (1) 
for the arms 

Steel rod(1) 

from a metals supplier 

Candle drip cups (2) 

/ bought them at Michaels. 

Threaded standoffs (4) 

Unthreaded spacers (4) 

Hard fiber washers (8-12) 

Machine screw (8) 


Tension pins (2) 

Wave spring washers (10-15) 

Shaft collars (3) 

Shoulder bolts (3 per jelly) 

© Make Projects 

Page 1 of 16 

Geared Candleholder 

Tapping oil (1) Binding post (4) 

• Thread locker (1) 

• Vised) 


Nothing says "machine" quite like a bunch of gears turning in time with each other. It's an 
iconic image. Unfortunately, gears are expensive and hard to find pre-made. You can 
scavenge them from discarded machines, but the selection is limited, and it's possible to 
amass a whole drawer of gears without having any two that actually fit together. 

When I began making kinetic sculpture, this was one of my major dilemmas. So I developed 
an easy and relatively fast technique for making my own gears out of metal plate that also 
has the advantage of giving them an inviting, toy-like appearance. 

Here's an elegant, all-aluminum candleholder with a movement containing 3 handmade 
gears. The drive gear or pinion on the left pushes 2 candle-bearing arms up and down on 
either side, and because of the different sizes of the gears, the candles move at different 

An 8-tooth drive gear or pinion gear turns 15- and 24-tooth driven gears, each of which 
moves a different arm. The 2 driven gears have a gearing ratio of 5:8, so the 2 candleholders 
reach the same relative position, such as maximum height, with every 8 revolutions of the 
smaller gear or every 5 of the larger one. Either way, it takes 120 teeth for an arm to transit 
its full range of motion, which corresponds to 15 full turns of the drive gear knob. 

Movable parallel arms hold the candles, using the same principle as the classic Luxo L-1 
desk lamp: the 4-bar, parallelogram linkage. On each arm, the lower pair of pivot points and 
the upper pair of candleholder anchor points are both vertical and 1" apart, and it's this 
relationship that keeps the candle cups level in any arm position. 

The gears move the parallel arms by means of a connecting arm, a simple crank linkage that 
converts rotary motion to reciprocating (back and forth) motion. 

© Make Projects Page 2 of 1 6 

Geared Candleholder 

Step 1 — Mark the gears. 

• The gears are made by drilling holes around a circle, and then cutting material away so 
that the spaces between the holes become the teeth. 

• Download patterns for the gears and all other project parts from the Documents section 
above. To calculate the radius of each gear's pitch circle, which runs through the center of 
the teeth, I used the formula: r = s * n where s is the tooth size and n is the number of 
teeth. I used a 1/4" drill, giving a 1/4" tooth size, so for my 8-, 15-, and 24-tooth gears, I 
got pitch radii of 0.637", 1.194", and 1.910", respectively. 

• Center-punch the center of each gear on the 1/4" aluminum plate and use a protractor and 
scribe to mark the angle position of each tooth gap. The 8-tooth gear needs a mark every 
45 , the 1 5-tooth gear every 24 , and the 24-tooth gear every 1 5 . 

• For each gear, use a straightedge to scribe lines radiating from the center out to the angle 
marks. Set a drafting divider to the pitch radius (I did this with a caliper) and scribe the 
pitch circle. Similarly mark the outer circles. On the 2 larger gears, mark lines to position 
the connecting arm holes, at 0.687" radius for the 1 5-tooth gear and 1.125" for the 24- 

© Make Projects 

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Geared Candleholder 

Step 2 — Punch, drill, and cut. 

• Wherever the pitch circle crosses the radiating lines, punch and drill a 1/4" hole. Also drill 
the center with the 1/4" bit. The connecting arm holes need to be tapped for 10-24 
threads, so punch then drill these with a #25 drill bit. 

• Cut the gear out as much as you can on a band saw. 

• CAUTION: Aluminum dust is very harmful. Wear a respirator and work in a well- 
ventilated space. 

• Finish the teeth by filing them until they are semicircular and even-looking. 


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Geared Candleholder 

Step 3 — Test and tap the gears. 

• Test-mount the gears onto a wood board using 1/4" bolts or rod. Leave a tiny bit of room, 
or "slop", between the gears to decrease the chance of binding. Turn them, and mark any 
problem areas for more filing. 

• To tap the holes for the connecting arms, clamp the gear so the hole location is off the 
edge of a table. Secure the 10-24 tap into the handle, put a couple drops of tapping oil on 
the tap, and screw it slowly into the hole. Apply light pressure, and turn back every quarter 
turn to break off the curls of metal. Go all the way through the hole before backing the tap 
out. Clean the hole, and screw in one of the 10-24 shoulder bolts to test the threads. 

© Make Projects 

Page 5 of 16 

Geared Candleholder 

Step 4 — Mark the body. 

© Make Projects Page 6 of 1 6 

Geared Candleholder 

• These gears are not precise, so 
you need to lay them out and adjust 
their relative distances before you 
machine the body pieces that they 
mount to. However, the distances 
to the arm pivot points are fixed 
and must be accurate. Follow the 
vertical and diagonal 
measurements on the pattern at, 
and within these constraints tweak 
the gears' relative horizontal 
positions so that they mesh 
effectively. Center-punch your 
marks, but hold off on drilling yet. 

• Tip: Use a combination 
square and a divider to 
mark vertical lines and distances 
from the bottom edge of the plate. 

• Follow the pattern to outline the 
body. Use your center marks to 
create the outline, scribing circles 
and connecting them with "necks". 
I used an oval drafting template to 
make smooth curves. 

• For the 2 feet, mark two 7/8"- 
diameter half-circles at the bottom. 
In the upper corners, mark 7/8"- 
radiuscircles (1-3/4" diameter) that 
encompass both arm pivot holes. 
Make the central circles small 
enough to show off the mechanism 
inside. The resulting outline will be 
fun and reminiscent of old 

© Make Projects 

Page 7 of 16 

Geared Candleholder 

Step 5 — Cut out the body. 

• Roughly cut the back panel of the 
body on a band saw and drill the 
holes. The 11/64" holes in the 
corners are for 8-32 machine 
screws that hold 1-1/2" threaded 
standoffs between the 2 panels. 

• Use the back panel as a template 
to mark the front panel. To improve 
visibility of the gears, make the 
middle area of the front panel a 
little smaller. Clamp the panels 
together and redrill the 1/4" holes 
for the pinion (the smallest gear) 
and the 1 1/64" arm holes through 
the back and front panel together. 
These are the only holes in the 
front panel. 

• Tap the holes for the larger gears 
on the back panel the same way 
you tapped the gears in Step 3. 

• For the pinion axle, which will 
connect to the knob, cut a 1" piece 
of 1/4" steel rod. Put one end 
through the center of the pinion and 
slip a clamp-on shaft collar on top. 
To join the collar and pinion, drill a 
1/16" hole down through both, off to 
one side, and use a small hammer 
to drive in a 1/16" tension pin. 

© Make Projects 

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Geared Candleholder 

Step 6 — Mark the knob and feet. 

• Make the knob the same way you made the gears, as a 5-tooth gear with 1/2" teeth (pitch 
radius = 0.796", marks every 72°). Drill and attach the knob to a shaft collar with a tension 
pin, the way you did the pinion above. 

• For the feet, cut two 4" lengths of 7/8" aluminum rod. They need 2 slots cut halfway 
through them, 1/4" wide and 1-1/2" apart. Put the feet in a vise and use a hacksaw to cut 
each side of the slot, and then saw diagonally across both to clear out material in between. 
Finish clearing out the slots with a coarse file until the body panels fit in them. You'll attach 
these feet with epoxy later. 

© Make Projects 

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Geared Candleholder 

Step 7 — Cut the arms. 

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• Each of the larger gears drives an arm that moves 2 parallel levers up and down. The 
other ends of these levers hold the candle bracket, forming a 4-bar parallelogram linkage 
that keeps the candle upright. All the holes need to be placed accurately for the movement 
to work. 

• Cut the arms. Refer to the connecting arms pattern under Documents. All measurements 
are based on the centers of the holes, so add some extra length for the ends, and grind or 
file the corners round. 

• Drill the holes. Some need to be 1/4" while others are 13/64". The connecting arms attach 
to the gears with 1/4"-diameter shoulder bolts and the parallel arms pivot on 1/4" threaded 
standoffs. The arm parts attach to each other and to the candle brackets using 13/64" 
binding posts. 

• Cut the spacers. Ten spacers of varying lengths hold the arms and gears at the correct 
distances between the front and back panels. Referring to the spacer plan online, cut the 
2" unthreaded aluminum spacers down to the lengths needed with a hacksaw. Cut them a 
bit long and then file them down to a hair short, to allow for free movement. 

© Make Projects 

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Geared Candleholder 

Step 8 — Make the candle brackets. 

• Cut two 2"-diameter discs out of the thinner (1/8" or 3/16") aluminum plate. Drill four 9/64" 
holes in each, following the bracket pattern online. 

• Cut four 2" lengths of the 1/2" x 1/8" aluminum bar, round the bottom corners, and cut and 
drill per the pattern. Each short length of bar needs 2 posts cut out of the top to fit into the 
holes in the disks. Use a file to round the corners of each post, and insert the bars into the 

• To fully test-assemble the brackets, I cut and drilled an extra bar to sit in between the 
others, then secured them together with the 3/8" binding posts. The posts should be snug 
and stick out about 1/16". 

Step 9 

• To stake down the posts, clamp the 
bracket in a vise, then position 
your center punch in the middle of 
each post and use a small hammer 
to drive it in gently, spreading out 
the aluminum slightly, like a rivet. 

• Tip: The aluminum will 
crack if pushed too far, so 
be gentle. 

• Use 3/8" binding posts to join the 
brackets to the parallel arms, then 
finish the holders by using epoxy to 
attach glass drip rings on top of the 

© Make Projects 

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Geared Candleholder 

Step 10 — Final Assembly and Finish 

© Make Projects Page 12 of 16 

Geared Candleholder 

• Before putting everything together, 
go back and finish the parts 
individually. File and sand the 
edges of the panels, the ends of 
the feet and bars, etc. Soften the 
edges of the panels, gears, candle 
disks, and knob. Make a final pass 
with Scotch-Brite pads or steel 

• Install the 8-tooth drive gear, axle, 
and knob. To hold the axle in place 
behind the back panel, slip a 
couple of wave spring washers 
over the end and secure it with the 
third clamp-on collar. You can 
adjust tension on the axle by 
pinching the spring washers 
between the collar and the panel. 

• Use a grinder or file to trim 1/8" off 
the end of each shoulder bolt so 
they won't stick out through the 
holes in the 1/4"-thick gears or 
panel. (The threaded ends of the 
bolts are 3/8" long.) 

• Attach the large gears to the holes 
tapped in the back plate with 5/16" 
shoulder bolts, adding wave 
springs or fiber washers on each 
side for tension so that the candle 
arms won't fall down. I added 2 
fiber washers behind and 3 spring 
washers in front of each gear. 

• Attach the connecting arm for the 
15-tooth gear with a 3/8" shoulder 
bolt through a 1/4" spacer. Attach 
the arm for the 24-tooth gear with a 
5/8" bolt through a 1/2" spacer. 

© Make Projects 

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Geared Candleholder 

• Referring to the spacer plan, add 
the front panel and the 4 pivot 
arms, connecting the long pivots to 
the connector arms with 1/4" 
binding posts. The arms pivot 
around 4 standoffs secured to the 
panels by 8 button-head machine 
screws, and are laterally positioned 
by matched-length pairs of 
unthreaded spacers slipped over 
the standoffs. 

• Attach the candleholders, and seat 
the panels in the feet. When all this 
is put together, the arms should be 
between the body panels, and 
secure but not tight on the gears. 
You may have to tweak the washer 
combinations; try several to find 
what works best. When you put the 
machine together for the last time, 
add some thread locker to the gear 
bolts and the binding posts to 
prevent them from coming undone. 

• Use epoxy to permanently attach 
the feet to the body. You're done. 
Congratulations IThis is not a 
simple project, and doing it mostly 
with hand tools is especially 
challenging, but the sleek look and 
smooth mechanical action of the 
finished product should be very 
satisfying. I hope this piece will not 
only provide a fun project for the 
home but also be a catalyst for 
more experimentation in 
mechanics. For additional 
information and photos, go to . 

© Make Projects Page 14 of 16 

Geared Candleholder 

Step 11 — Crank Up the Atmosphere 

• This candleholder makes an 
excellent centerpiece at the dinner 
table; being transformable means it 
can change to fit the occasion. Lots 
of big serving bowls on the table? 
Lift the candles up high so they 
shine down on all the delicious 

• Given the time and craftsmanship 
that goes into its creation, this 
project also makes a wonderful gift. 
I gave a similar candleholder to 
friends of mine at their wedding, 
and they told me it was the most 
beautiful object they own. 

Step 12 — Variations 

• The dimensions and materials for this project are quite variable. You can use steel, 
plywood, or acrylic for the parts without a problem, except for tapping threaded holes. For 
plastic or wood, try threaded inserts such as McMaster-Carr part #99362A500. 

• The body shape and arm length can change to suit your desires. Just make sure the 
candle cups don't collide and the connecting arms don't hit the axle. If you're not sure 
whether your adaptation will work, make a cardboard mock-up and try it out. 

• The design is also expandable: imagine a whole row of candles, each rising and falling at 
different speeds! 

© Make Projects 

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Geared Candleholder 

Step 13 — Become a Gearhead 

• Once you understand the way this type of mechanism works, you can adapt it to an infinite 
number of projects. Being able to make your own gears and levers allows you to create 
exactly the movement you want, whether it's for a walking robot or a machine that brushes 
your teeth and ties your shoes! 

• Check out the resources below to add to your mechanical vocabulary and inspire your 
inner kinetic sculptor. 

• Resources 

• Flash animations showing how different movements and mechanisms work: 

• Useful animations and explanations of mechanisms: . 

• My website, with images and video of many mechanical sculptures, as well as links 
toother kinetic sculptors and resources: 

• 507 Mechanical Movements: Mechanisms and Devices by Henry T. Brown (Dover, 
2005) is a classic book of ideas for creating movements. 

• Illustrated Sourcebook of Mechanical Components by Robert O. Parmley (McGraw-Hill, 
2000) is a compendium of ideas for mechanical inventors. 

Related posts on Make: Online: 

Intern's Corner: Building the Geared Candleholder 

Benjamin Cowden Interview 

This project first appeared in MAKE Volume 21 

This document was last generated on 2012-1 1-03 12:14:55 AM. 

© Make Projects Page 16 of 16